Human spines are commonly prepared for implanting an artificial disc between two adjacent vertebrae which present two adjacent surfaces facing each other along the spinal column. The procedure of implanting an artificial disc is performed by a surgeon when a person's natural disc is defective. There may be a ruptured or herniated natural disc, and thus the need for the surgical repair consisting of the replacement of the natural disc with an artificial disc. The artificial disc may be man-made and of metal or plastic materials, and its size and shape should be that of the natural disc where the surgery is to restore the spine to a healthy condition.
The space between the two adjacent vertebrae surfaces which face each other along the spinal column is first cleaned by the surgeon and the remaining cleaned space is then to be gauged to determine the height and the angulation between those two surfaces. That is preparatory for the insertion of an artificial disc implant which should snugly occupy the space for desired spinal supportive action.
It is an object of this invention to accurately and efficiently determine the size of that cleaned spaced so that a most appropriate size and shape of artificial implant can be positioned between the two vertebrae. Because this disc implant surgery is approached from the anterior of the patient's torso, it is necessary to negotiate the patient's body parts which normally lie on the path extending from the anterior to the spine. For instance, for the site between the patient's fifth lumbar vertebra and the adjacent first sacral vertebra that site can be approached along a frontal line from the anterior to that site. Therefore, one tool and trial or gauge block arrangement can be employed for accessing that site.
However, other sites along the spine, and the lordotic ones are the ones under consideration herein, that is, those along both the lumbar and cervical spinal lengths, may require an approach which is laterally offset from the full anterior frontal approach mentioned above. That offset is with regard to the approaches, except the one mentioned above, where the patient's aorta is on the access line between the anterior and the spine site.
To accomplish the aforementioned two approaches, this invention provides for two lines between the anterior and the vertebrae sites. This provides for the accurate gauging of the site space height and the tapered angulation between the vertebrae surfaces as they exist on the lordotic vertebrae. A kit of a plurality of different sizes and shapes of gauge blocks or trials, and one tool which can fit all the blocks, can be provided to achieve the implanting of the variety of implant sizes required for optimum restoration of the lordosis of the spine. In the ultimate, there can be a first plurality of blocks which have only one maximum height but which have different angulations or tapers for determining the lordotic angulation of various first sites which are at that one height. Then there can also be a second plurality of blocks at a second height and with their different angulations or tapers for determining the lordotic angulation for various second sites different from the first various sites. Additional pluralities of blocks can also be provided.
The gauge blocks or trials of this invention are provided in kit arrangement in that they are in a plurality and are selected by the surgeon for individual use in determining the size of the vertebrae space in which an artificial implant is to be placed for permanent installation. Thus, the surgeon can select the optimum height and shape or taper of the implant after the surgeon has explored the site by sensing with the gauge block. In those instances, the sites are of the tapered lordotic shape, and therefore they are in the lumbar and cervical lengths of the spine. That shape is such that the space is higher at the anterior side of the spine, compared to the posterior side, that is, it is tapered down to the rear of the spine. According to the patient, the height and taper of any particular site can differ from that of another patient. So, for instance, a collection of say six blocks, all at a maximum height of say 11 mm at the highest location of the taper, can each have their own individual angulation of taper, such as 4, 5, 6, 7, 8, and 9 degrees. Other heights and angulations can also be provided to match the variety of vertebrae spacing and patients.
Further, each block can be arranged for accommodating the two angularly related anterior approaches, thus the kit is doubled in its versatility for the various approaches. Still, each gauge block can be inverted for spinal approaches from either lateral side of the patient.
Both the assembly of the blocks with the tool and the method of producing and applying same are disclosed herein.